Using sustainable design and construction solutions is often, by a happy coincidence, more affordable than ‘regular’ building techniques. This is due to the efficiencies and optimisations required to make a successful low energy building. Affordable Passivhaus construction was a running theme throughout the lectures at the International Passivhaus Conference this year, with delegates enthusiastically sharing their ideas.
As the global rhetoric shifts towards near-zero energy building, a growing community is turning to Passivhaus as a tool to control climate change. And as the demand for sustainable construction increases, the cost of the high-performance components (insulation, windows & ventilation) comes down. Even so, the additional investment that remains seems to make Passivhaus less financially attractive to some. In response, the Passivhaus community is constantly sharing techniques that make energy efficient construction financially comparable to a ‘regular’ build. This post considers 5 such tips I picked up whilst at the conference:
#1 The ringmaster
Wherever possible, have one person in control of site works throughout the construction of a Passivhaus project. Their investment in the success of the build will permeate throughout the site, inspiring all those involved to join in the commitment to achieve an exemplary build. Their passion will prevent the disillusionment of the site workers, thereby minimising the risk of costly mistakes being made.
#2 Multi-talented trades
When designing the building, carefully consider site sequencing across the suite of construction details as division of labour drives up the costs considerably. Once on site, using cross-discipline tradespeople will result in more affordable construction. Being able to assign tradespeople to alternative tasks when required optimises the workflow, saving time and money.
#3 Minimise waste
Use board dimensions to plan out the size of the rooms to reduce waste. When the site conditions permit, carry out onsite assembly of pre-cut elements. This reduces transportation costs and crane use when compared to a fully prefabricated solution, yet still ensures that waste is minimised.
#4 Put away the calculator
Thermal bridges are areas within the external envelope that are less effectively insulated than the remainder of the building. It’s at these points that heat loss is exaggerated and cold spots are prevalent, leaving them vulnerable to mould growth. Building Regulations recognise this risk and require the heat transfer rate of thermal bridges to be calculated and assessed. Passivhaus takes this further, with the aim of achieving a thermal bridge free construction. It is often easier and cheaper to design out thermal bridges than to calculate their impact – with the added benefit that it also makes the building healthier and more comfortable to be in.
#5 Rationalise the windows
Wherever possible, it is preferable, both in terms of budget savings and energy efficiency, to have one large window instead of several smaller ones. Generally, triple glazing performs better than the frame surrounding it, so if you bring the perimeter to area ratio down, the windows will be far more efficient. Replacing a series of small windows with one large window is a classic example of a sustainable solution saving money – fewer windows means a reduction in cost for materials, manufacture, delivery and installation.